This invention, generally, relates to the field of simulation and, more particularly, to a new and improved control circuit for a servo motor.
Usually, an electrical servo motor operates from continuous analog signal inputs. However, present day simulators are driven by computer, which means that the signal inputs to control such an electrical servo motor are digital in form and are modified, or updated, only at the iteration rate of the computer.
It is well known from past experience with servo motor controls, in the computer field particularly, that digital data can be modified with greater accuracy than can analog data, and in addition, digital data has a higher immunity to noise. Whenever a servo control circuit is designed for high accuracy and high dynamic range, therefore, it is perferably in the digital format.
There is a requirement in the simulation field for a servo control to far exceed the normal control, i.e., such servo control should accept computer inputs at the computer's iteration rate; yet, provide pseudo continuous inputs to the servo motor. For example, such control in a simulator must be rapid and continuous to afford the kind of effectiveness required in the simulator field.
The types of servo control circuits available in this field, for example, to move a large gantry only a fraction of a centimeter, results in motion that is irregular, jerky, and discontinuous at the best. It is far from accurate, and when used to move a projector's line-of-sight in larger visual systems, the result is highly detramental to the realism sought to be achieved.
The servo control circuits available to move a projector's line-of-sight, therefore, must be limited in bandwidth or must have filters on the computer inputs in order to provide the smooth and continuous movement required to achieve the realism needed. The result is the loss of accuracy and the addition of delay, both highly detramental to realism.